1. Field of the Invention
This invention generally relates to an equipment for facsimile call service of a telephone exchange and, more particularly, to an equipment for facsimile call service of a telephone exchange which can apply an unique charging system to a facsimile call by distinguishing the facsimile call from a speech call, notify a caller of cause when occurring a failure in transmitting the facsimile call, and advice the caller on the way to eliminate the cause.
2. Description of the Prior Art
Up to this time, an overseas facsimile communications network has been made by connecting subscriber facsimiles to respective subscriber lines. The demand for such a facsimile communication rapidly increases as overseas business expands. The facsimile communication generally has the advantages of finishing caller's work even if the callee is not there and making transmission time shorter than speech communication.
All kinds of communication, such as facsimile, data communication or the like, passing through telephone exchanges is processed in the same manner as the speech communication since these communications can not be distinguished from the speech communication at the telephone exchanges. Also, the facsimile communication is made using local telephone lines, so that an ordinary telephone call charging system is applied thereto. For this reason, any caller will be charged for the call even if the caller has not completed his or her work due to a failure of the facsimile transmission, and this has caused a problem that an appropriate communication system has not yet realized by making a good use of properties unique to the facsimile communication but not the speech communication.
Further, when failing in the transmission, no subscriber can know information other than the result of "transmission error" displayed on his or her facsimile since the transmission is made between the facsimiles. Therefore, in order to transmit document information to the receiving side, the sending side has no other way than to repeatedly transmit the document till the transmission is achieved successfully without knowing the reason for the transmission error. Particularly, when the facsimile transmission through the international telephone network was not completed by an unknown reason, the subscriber of the sending side must attempt the transmission many times without success since he or she can never know the reason.